Salmonella enteritidis phage types in Germany

In order to monitor the epidemiological situation ofS. enteritidis in Germany, in 1990–91 1138 isolates from more than 180 locations in West Germany were phage typed. 1124 strains (98.8%) from all sources were typeable, belonging to 21 different phage types (PT). PT4 strains were isolated most frequently (70.8%). In addition, PT7, 25, 34 and 8 were of epidemiological relevance with incidences of 7.2 to 4.5%. The comparison of data shows that in Germany, like in other parts of Europe, PT4 predominates. This phage type is, however, infrequent in North America, where PT8 has the highest incidence.     

Distribution of Salmonella enteritidis phage types in Canada

The distribution of Salmonella enteritidis phage types in Canada is described; 606 of 674 strains examined were of human origin. Typable strains of all sources, constituted 99.6% (671/674) of all strains examined, and were representative of 15 different phage types. Five phage types (8, 13, 4, 13a and 1) accounted for 92.4% of the total. Phage type 8 consistently showed the highest incidence in human (69.96%) and non-human (72.05%) sources and appeared to be the most common in North America. Phage type 4, the most prevalent in the UK, is infrequent in Canada (38/674). The distribution of phage types showed regional variation among infrequent phage types, whereas the common type, 8, was observed in different frequencies in all provinces. Examination of 29 outbreaks of S. enteritidis representing 254 isolates for humans revealed 5 different phage types, the highest number of outbreaks (11) were type 8. A study of these outbreaks and the animal-host-associations of the common phage types, 8 and 13, indicated that contaminated poultry appeared to be the most common source of human infection in Canada.     

Molecular characterization of plasmids in Salmonella enteritidis phage types.

Plasmids in selected type strains of 26 of the Salmonella enteritidis phage types have been characterized by restriction enzyme fingerprinting and by DNA-DNA hybridization with oligonucleotide probes for Salmonella plasmid virulence (Spv) genes. With one exception, the fingerprints of the 38 MDa plasmids studied were homogeneous but there was heterogeneity in the fingerprints of 59 MDa plasmids found in 4 of the type strains. However all 38 MDa and 59 MDa plasmids were related as was a 45 MDa plasmid identified in the type strain of phage type 19. A 3.5 kb fragment homologous to SpvC was conserved in Hind III digests of all 38 MDa and 59 MDa plasmids, and in the related 45 MDa plasmid. In contrast a 65 MDa plasmid found in the type strain of phage type 10 was not related to these three plasmid molecular weight groups and did not carry the SpvC gene.     

Subdivision of Salmonella enteritidis phage types by plasmid profile typing

Differentiation of Salmonella enteritidis by plasmid profile typing has been compared to differentiation by phage typing. Examination of the type strains of the 27 S. enteritidis phage types showed that only 11 profile patterns could be identified. Moreover, two profile patterns were found in 15 of the type strains, including those of the two most common phage types in Britain, types 4 and 8. On this basis, plasmid profile typing is not as sensitive as phage typing for the primary subdivision of S. enteritidis. When differentiation of 534 strains of the 27 phage types was attempted using plasmid profiles, variation in pattern suitable for epidemiological subdivision was found in 13 phage types and there were 9 profile patterns in strains of phage type 4. Plasmid profile typing can, therefore, be regarded as an effective adjunct to phage typing for the subdivision of S. enteritidis.     

A comparison of Salmonella enteritidis phage types from egg-associated outbreaks and implicated laying flocks.

Infections due to Salmonella enteritidis are increasing worldwide. In the United States, between 1985 and 1989, 78% of the S. enteritidis outbreaks in which a food vehicle was identified implicated a food containing raw or lightly cooked shell eggs. Under a US Department of Agriculture regulation published in 1990, eggs implicated in human food-borne S. enteritidis outbreaks were traced back to the source flock. The flock environment and the internal organs of a sample of hens were tested for S. enteritidis. We compared the S. enteritidis phage types of isolates from 18 human, egg-associated outbreaks and the 15 flocks implicated through traceback of these outbreaks. The predominant human outbreak phage type was recovered from the environment in 100% of implicated flocks and from the internal organs of hens in 88% of implicated flocks we tested. The results support the use of phage typing as a tool to identify flocks involved in human S. enteritidis outbreaks.     

Antimicrobial susceptibility and phage types of Salmonella enteritidis strains isolated in the Lublin area

The study aimed at specifying the value of two traditional methods of typing, using the collection of 241 strains of Salmonella Enteritidis isolated from people and animals in the Lublin area in 1994-1995 from the occasional cases of infections. There were 8 phage types identified among the examined strains. Phage types PT 6 (40.24% of strains) and PT 7 (29.46%) were the most numerous ones. Salmonella Enteritidis was numbered among 38 profiles on the basis of the analysis of resistance to 15 antimicrobial agents. It was found that nitrofurantoin had the lowest efficacy in vitro in relation to the examined collection of Salmonella isolates. High percentage of strains were characterized by lack of susceptibility to streptomycin, neomycin, cefixime, tetracycline and canamycine. While analyzing the profiles of resistance to chemiotherapeutics and the expression of phage type of the examined strains it was observed that only 14.1% of all strains showing resistance to nitrofurantoin represented at the same time phage type PT 6, whereas 10.8% of strains belonging to the same resistance profile indicated PT 7 phage type. In correlated analysis of resistance to chemiotherapeutics and phage type expression of the examined collection of 241 isolates of Salmonella Enteritidis, 18.3% of strains showed distinct and unique set of these two features, which can be used in epidemiological investigations for the preliminary characterization of the bacterial population.     

Comparison of two Salmonella enteritidis phage typing schemes

The comparison of two phage typing schemes for Salmonella enteritidis was performed. A total of 517 strains were phage-typed according to the schemes of Lalko [27] and Ward et al. [21]. Strains were isolated from food-poisoning outbreaks and other common sources in Poland, between 1986–1995. Above 99% of all strains tested were differentiated to the definitive phage type using the Lalko collection of typing phages. Phage types 1 and 7 (PTs 1, 7) were the most isolated. The typing phages of Ward enabled to assign 56.5% of all strains (a total of 14 phage types were presented), 37.1% – reacted with phages without showing any of the designated phage types and 6.4% were untypable. Phage type 8 (PT8) predominated. The majority of Salmonella enteritidis strains from one phage type outbreaks of Lalko presented different types of lytic reactions with the Ward phages. Only the correspondence of Salmonella enteritidis PT7 of Lalko with PT8 of Ward et al. [21] was observed.     

Outer membrane characteristics of Salmonella enteritidis phage type 4 growing in chickens.

Strains of Salmonella enteritidis belonging to phage type 4 (SE4) were grown in the peritoneal cavities of chickens, and without subculture on laboratory media examined for inducible in vivo phenotypic characteristics. These bacteria expressed three major outer membrane proteins (OMPs) of 33, 35 and 36 kilodaltons (kDa), and iron regulated OMPs of 74, 78 and 81 kDa. Bacteria growing in vivo did not express flagella, or fimbriae with a subunit molecular mass of 14 kDa (14 kDa fimbriae). Two OMPs of 55 and 23 kDa, expressed during culture in nutrient broth, were repressed during growth in chickens. Possession of a 38 MDa ''mouse virulence'' plasmid did not influence the expression of OMPs, flagella or fimbriae. It was concluded that strains of SE4 growing in chicken tissues, use an enterobactin mediated iron uptake system to obtain ferric ions, do not express flagella or 14 kDa fimbriae and appear not to express novel OMPs involved in survival in vivo.     

Correlation of change in phage type with pulsed field profile and 16S rrn profile in Salmonella enteritidis phage types 4, 7 and 9a.

Using pulsed-field gel electrophoresis (PFGE) and 16S rRNA (rrn) analysis (ribotyping), the in vivo derivation of strains of Salmonella enteritidis PTs 9a and 7 from a strain of S. enteritidis PT 4 has been demonstrated. All strains were isolated from a single patient over a 6-week period. Further studies have demonstrated that in terms of pulsed-field profile and ribotype, the genotypes of the patient-derived strains differed from those of the reference strains of the respective phage types. It is concluded that when used in combination, these methods can provide evidence of phylogenetic relationships in apparently unrelated S. enteritidis phage types isolated during pathogenesis of disease.     

Vaccination of chickens with chicken-derived Salmonella enteritidis phage type 4 aroA live oral Salmonella vaccines.

Two strains of Salmonella enteritidis phage type 4 isolated from chickens, SeLA5 and Se267, were virulent in Balb/c mice by intraperitoneal (i.p.) infection. In 18-20-day-old chickens given 10(7) c.f.u. intravenously (i.v.), both strains caused some deaths. One-day-old chicks infected orally with 10(9) c.f.u. of either strain also suffered limited mortality. Strain SeLA5 was the more virulent by the oral route. AroA mutants SeLA5 aroA and Se267 aroA were reduced in i.p. virulence by up to six logs in the Balb/c mouse model, did not kill 18-20-day-old chickens when injected i.v. and did not multiply in the tissues. Oral vaccination of chicks with either 10(9) c.f.u. at one-day-old or 10(5) c.f.u. at seven-day intervals until day 21 with vaccine strains SeLA5 aroA or Se267 aroA conferred significant protection against intravenous challenge with virulent strain Se109 NalR and reduced intestinal shedding following oral challenge. Seroconversion following oral vaccination was not seen with the lower dose regimen and was low with the higher dose. Seroconversion following oral challenge was marked in unvaccinated birds but much lower in vaccinated birds, suggesting that oral vaccination had prevented invasion by the challenge strain.     

14个省市区鼠伤寒沙门氏菌噬菌体型的动态分析

从收集到的３８４１株鼠伤寒沙门氏菌的噬菌体分型结果，分析鼠伤寒沙门氏菌噬菌体型在１４个省市自治区的流行动态。７７７４株在各地广泛分布于并常中首位，主要引起感染性腹泻，也民食物中毒和医院内感染。高峰期在１９８７－１９９１年。１９８７年在福建发生的一起最在的７７７４型食物中毒，患者有１１１３人，７７７６型主要在新疆流行，高峰期在１９９３年。０７７４型是１９８９－１９９１年间在河南各地广泛引起医院内感染     

A large outbreak of Salmonella enteritidis phage type 4 associated with eggs from overseas.

In February 1989 the largest reported outbreak to date in the United Kingdom of Salmonella enteritidis phage type 4 (PT4) infection occurred following a wedding reception at a hotel. One hundred and seventy-three people met the case definition of illness of whom 118 had the organism isolated from their stools. A further 17 were found to be S. enteritidis PT4 positive, but were asymptomatic. Lightly-cooked, egg-based sauces were the epidemiologically proven vehicles of infection. Investigations showed this outbreak to be the first to implicate imported European eggs as the source of infection. An unusual feature of this outbreak was a reported incubation period of less than 3 h for some of the confirmed cases of salmonellosis.     

Acquisition of a drug resistance plasmid converts Salmonella enteritidis phage type 4 to phage type 24

Salmonella enteritidis accounted for 55% of the 27,478 salmonellae isolated from humans in England and Wales during 1988. Within this serotype phage type 24 has increased from 24 isolations in 1987 to 201 in 1988. The high frequency of drug resistance in this phage type has been shown to be due to the presence of plasmids belonging to Inc N and coding for resistance to a range of antimicrobial drugs among which resistance to ampicillin, streptomycin, tetracycline (AST) and T predominate. These plasmids are phage-type determining and convert strains of phage type 4 to phage type 24.     

Occurrence of phage types of non-typhoid Salmonella serovar in the Slovak Republic 2000-2003

Salmonellae of non-typhoidal serovars are the most important pathogens involved in foodborne diseases in humans all over the world. The incidence rates of two major Salmonella serovars, i.e. S. enterica serovar Enteritidis (S. Enteritidis) and S. enterica serovar Typhimurium (S. Typhimurium), in the Slovak Republic in 2000-2003 are given. Over the period studied, 829 S. Enteritidis strains and 258 S. Typhimurium strains isolated from patients with salmonellosis were investigated in the National Reference Centre for Salmonella Phage Typing. The S. Enteritidis strains were differentiated into 16 phage types, with phage type 8 being dominant since found in 73.6%, 53.8%, 62.8% and 45.6% of strains in 2000, 2001, 2002 and 2003, respectively. The following most frequent phage types were 4 and 13a. New phage types, i.e. 15, 5, 25 and 14b, were identified from salmonellosis outbreaks in 2003. The S. Typhimurium strains were also differentiated into 16 phage types with phage type DT104 strains being prevalent and showing an increase from 7.4% in 2000 to 44.6% in 2003; 54.2% of them were resistant and of R type ACSSut. The second most frequent phage type in 2000-2001 was 2b in 2003 DT41. The frequency of the other phage types was not epidemiologically significant.     

Nosocomial Legionnaires' disease in England and Wales, 1980-92.

Two hundred and eighteen nosocomial cases of Legionnaires'' disease with 68 deaths were reported to the National Surveillance Scheme for Legionnaires Disease between 1980 and 1992, representing 15% of the reported infections acquired in England and Wales. Twenty-two nosocomial outbreaks accounted for 135 (62%) of these cases, the remainder occurring as single cases either in hospitals where other single cases or outbreaks had been reported in different years or as ''sporadic'' cases in hospitals from which no other cases were reported. A clinical history prior to onset of Legionnaires'' disease was available for 124 patients, 61 of whom had undergone recent transplant therapy or were immunosuppressed for other reasons. Sixty cases (27%) were diagnosed by culture of the organism and isolates from 56 patients were typed; 25 (42%) were non L. pneumophila serogroup 1 infections. Methods for prevention and control of nosocomial outbreaks are discussed, in particular the susceptibility to Legionnaires'' disease of certain groups of hospital patients.     

Molecular epidemiology of Salmonella enteritidis phage type 1b and 6a isolates in Portugal

Salmonella enterica serotype Enteritidis is an important serovar comprising 76 % of Salmonella isolates in Portugal in 2001. For better understand the epidemiology of salmonellosis, a total of 47 isolates of S. Enteritidis phage type (PT) 1b and 6a were analysed by pulsed-field gel electrophoresis (PFGE) and genomic DNA was subjected to macro restriction with XbaI. For PT 1b isolates, only three different patterns were observed, and PT6a showed a total of 10 digestion patterns. Curiously, the main pattern among PT1b isolates seams quite similar to main pattern of PT6a isolates, but when the two patterns were analysed with Bionumerics, we observed that they exhibited some differences. It was concluded that, in 2001, there was one predominant pattern for PT1b and PT6a and, possibly, we were in presence of clonal strains that exists all over the country.     

Four linked outbreaks of Salmonella enteritidis phage type 4 infection--the continuing egg threat

Four outbreaks of Salmonella enteritidis phage type (PT) 4 occurred among guests at functions for which a single commercial caterer supplied food. Retrospective cohort studies were used to describe the epidemiology of three of these outbreaks and identify the vehicle(s) responsible. Of 172 guests at these three events, 47 fitted the clinical case definition for illness and 24 cases were confirmed to have S. enteritidis PT4 infection. Food containing raw egg was identified epidemiologically as the likely vehicle of infection in two of the three outbreaks (odds ratios (OR) and 95% confidence intervals 9.1 (2.2-39.9) and 6.9 (1.2-46.4)). Logistic regression analysis yielded OR = 10.7 (p = 0.0022) and OR = 9.3 (p = 0.015) for egg consumption in two of the outbreaks. These outbreaks highlighted the continuing need to remind the public and commercial caterers of the potential high risks of contracting salmonella from shell eggs. Education of caterers includes advice to obtain eggs and other products from reputable and identifiable suppliers.